Blake Robert Johnston (42), who was described as a "cyber monster", was sentenced by a California court last year to 30 years in prison for travelling across state lines in the US with the intent of engaging in sexual acts with a minor.
His crimes came to light following the disappearance of a 14-year-old girl in Oregon in October 2014. The girl's mobile phone records and computer history led police to Johnston and, within 24 hours of her going missing, the girl was traced to his home in Martinez, California.
Johnston was convicted for sex offences relating to the girl.
During a search of Johnston's bedroom, investigators seized a hard drive which contained around 500 folders labelled with different female names. The majority of the folders were found to contain images and/or video of child pornography which no investigators had previously encountered, indicating that these were victims whom Johnston had groomed personally.
Investigators have so far identified 94 victims, who come from across the US and from at least six countries, including Ireland, the UK, Australia, Canada and Malaysia. Authorities in those countries are assisting their US counterparts in the investigation.
RTÉ's 'This Week' reported that as many as four Irish children, and possibly more, are among Johnston's victims.
The US Attorney's office for Northern California told RTÉ that of the four Irish children, one was based in Dublin and another lived in Co Meath. The exact location of the third child had not yet been identified, while the fourth child had moved between Ireland and another jurisdiction when the abuse occurred.
Johnston admitted to police that he contacted children using a number of different messaging apps and websites.
Investigators used a variety of methods to identify the victims, including examining school crests seen in footage as well as other items on display in the background of the images.
Commenting following Johnston's sentencing last year, Ryan L Spradlin, Homeland Security Investigations special agent in charge, said: "A cyber monster's perverse desires often turn into physical victimisation and a child's worst nightmare.
"While we are satisfied with the 30-year sentence for the horrific crimes committed, we must remember the young victims who are left with permanent psychological, physical and emotional scars."
Sentencing Johnston, Judge Jeffrey S White said his conduct was "unusually heinous", adding that he had "preyed upon (the child victims') low self-esteem" and used "extreme cunning, guile, intelligence, strategies, and a lot of thought and a lot of skill".